Power transmission

ABSTRACT

Turbocharger drive having planetary gear units in a gear train between an engine crankshaft and a compressor rotor, which rotates to supply air to an engine for combustion. The reaction member of a planetary unit of the gear train is connected to the pump of a hydrodynamic unit while the turbine member is grounded so that the stall torque of the unit retards rotation of the reaction member to permit the engine crankshaft to drive the rotor through the gear train. The hydrodynamic unit having an infinite number of spring rates provides an infinitely flexible device for reducing transmission of engine torsionals and shock loads through the gear train. The mechanical drive is assisted by a gas drive from the engine exhaust which progressively increases as the engine approaches full load and the rotor becomes fully driven by the engine exhaust gases. When the gas drive speed and load equals the rotor needs, the mechanical system reaches a noload condition.

United States Patent Apr. 17, 1973 Duerr POWER TRANSMISSION [75]Inventor: Bruno A. Duerr, La Grange Park,

Ill.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

[22] Filed: July 2, 1971 [211 Appl. No.: 159,210

[52] US. Cl ..74/782, 74/675 [51] Int. Cl ..F16h 3/00 [58] Field ofSearch 74/782, 675; 60/13 [56] References Cited UNITED STATES PATENTS2,390,626 12/1945 Szekely ..74/782 3,007,302 11/1961 Vincent......74/675 3,382,855 5/1968 Glamann ..60/l3 Primary Examiner-C. J.l-lusar Attorney-W. E. Finken et a].

I 57 ABSTRACT Turbocharger drive having planetary gear units in a geartrain between an engine crankshaft and a compressor rotor, which rotatesto supply air to an engine for combustion. The reaction member of aplanetary unit of the gear train is connected to the pump of ahydrodynamic unit while the turbine member is grounded so that the stalltorque of the unit retards rotation of the reaction member to permit theengine crankshaft to drive the rotor through the gear train. Thehydrodynamic unit having an infinite number of spring rates provides aninfinitely flexible device for reducing transmission of enginetorsionals and shock loads through the gear train. The mechanical driveis assisted by a gas drive from the engine exhaust which progressivelyincreases as the engine approaches full load and the rotor becomes fullydriven by the engine exhaust gases. When the gas drive speed and loadequals the rotor needs, the mechanical system reaches a no-loadcondition.

6 Claims, 1 Drawing Figure g is 7A 2 u I i s i I I PATENTEDAPR 1 1 1m'3'. 727. 485

IINVENTOR. razzo 14.11am? ATTORNEY POWER TRANSMISSION This inventionrelates to power transmissions and more particularly to a transmissionfor a turbocharger providing for the one-way transmission of powerbetween an engine crankshaft and a rotor unit of the turbocharger.

Prior to the present invention, engine turbocharger drive systems haveincorporated a one-way clutch to permit the engine crankshaft to drive aturbocharger rotor unit comprising the a turbine wheel and connected aircompressor impeller. These clutches are generally of the ratchet orroller type and are effective to permit the crankshaft to drive therotor unit until the energy from the engine exhaust converted by theturbine wheel drives the rotor unit without the aid of the gear train.When this occurs, the one-way clutch disengages to permit the rotor unitto overrun the drive from the crankshaft. While these prior gear trainshave been quite satisfactory, the one-way clutches are subjected tosevere loading and wear because of transmission of engine and outputshaft torsionals through the gearing.

In the preferred embodiment of the present invention the stall torque ofa fluid unit such as that of a torque converter or fluid coupling isemployed to retard rotation of a reaction member of a planetary gearunit forming part of the gear train between the engine crankshaft and arotor unit in a turbocharger. This permits the engine torque to bemechanically supplied to drive the turbocharger rotor unit with a smallpercentage of torque being passed to the fluid unit. The engineturbocharger drive system of this invention further permits the rotorunit to overrun the mechanical drive from the engine crankshaft withoutthe prior one way clutching mechanism and the slip characteristics ofthe fluid unit can be used to limit the rotor over-speed. The employmentof a fluid unit in the present system as a reaction member divides thesystem into two parts without the use of prior one way clutches andprovides an infinitely flexible reaction member to reduce thetransmission of engine torsionals. Also, shock loads such as thoseoccurring when there is abrupt transfer of the drive from the rotor unitto the gear train are absorbed without undue strain on the gearing. Whenthe engine is under a no-load condition as when idling, the fluid unitslippage absorbs part of the torque so that the drive torque for theturbine wheel is reduced thereby reducing the output of the compressorimpeller which decreases fuel consumption and extends gear train life.With this system the hydraulic unit can be employed in apositionvoutside of the turbo assembly housing in a convenient place forservicing.

The gear train of this invention preferably has a gear ratio which isoptimized to take advantage of slip in the hydrodynamic unit to simulatethe clutch overrun, however, the fluid in the unit can be dumped foroverrun, if desired. Also, a small one-way clutch can readily be usedbetween the reaction gear of the planetary unit and the pump of thehydrodynamic unit or between the turbine of the hydrodynamic unit andground to permit the overrun of the rotor unit.

These and other features, objects and advantages of this invention willbecome more apparent from the following detailed description and drawingin which:

The F lGURE shows a side view partly in section of an engineturbocharger drive system.

As shown in the FIGURE there is a crankshaft 10 of a diesel or othercombustion engine having a crankshaft gear 12 that meshes with anddrives an idler gear 14. This idler gear is rotatably mounted on a stubshaft 16 extending from a stationary plate 18 that is secured by boltsto the end plate 19 of the engine crankcase. ldler gear 14 meshes withand drives an idler gear 20 rotatably mounted on stub shaft 22 extendingfrom end plate 18. This latter idler gear is drivingly connected to aplanetary gearset 24 preferably by connecting the pivot shafts 26 ofplanet gears 27, which extend from carrier 28 to the web of the idler.The planet gears 27 mesh with a ring gear 30 and a sun gear 32 of theplanetary gearset 24. The sun gear 32 is disposed at one end of anaxially extending shaft 33, which has at the other end a spur gear 34,which meshes with a spur gear 36 that is drivingly connected to the pump38 of a fluid unit 40, which in the preferred embodiment, is a fluidcoupling. The fluid unit has a turbine 42 fixed to a stationary housing44. When operating, the fluid unit is supplied with three to fourgallons of engine oil per minute through a supply passage 43 and the oilexiting from this coupling is fed by passage 45 to a cooler 47 and thento a sump, not shown.

The ring gear 30 of the planetary gearset 24 is drivingly connected to aturbocharger drive gear 48, which meshes with and drives an idler gear50. As shown, gear 48 is mounted on a sleeve 51 supported in housing 52while idler gear is rotatably mounted in housing 52 and meshes with acarrier drive gear 54, which is splined to a shaft 56. This shaft isdrivingly connected to a carrier 58 for the'planet gears 60 of aspeed-increasing planetary gearset 62. The planetary gears 60 aremounted on pivot pins extending from the carrier. These gears mesh witha stationary ring gear 64 and a rotatable sun gear 66. The sun gear,providing an output of this planetary gearset, is fixed on one end of ashaft 68 which is drivingly connected to a bladed turbine wheel 70 and abladed impeller 74 which form a rotor unit 75. Air is taken into thecompressor housing through air inlet 76 and compressed by the rotatingimpeller and supplied through discharge scroll 78 through suitableductsto the engine induction system. In addition to the drive from the geartrain described above, the bladed turbine wheel 70 and connectedimpeller can be driven by the hot exhaust gases from the engine suppliedto the turbine inlet scroll 80 through engine exhaust manifold 81.Engine exhaust gases fed to the bladed turbine wheel 70 are exhaustedthrough the exhaust duct 82.

To provide the necessary air for combustion for engine starting, lightload operation and rapid acceleration, the rotor unit with the aircompressor impeller 74 is primarily driven by the engine crankshaft 10through the gear train and secondarily driven by the engine exhaustsupplied to the turbine wheel 70 through the inlet scroll 80.

When the engine is driving under these operating conditions, theplanetary gearset 24 is conditioned for overdrive operation; carrier 28being driven by the crankshaft 10 through idler gears 14 and 20 with thespeed of the reaction sun gear 32 fixed by the stall torque of the fluidcoupling 40. The stall torque rapidly increases with increasing speedand slip of pump 38 The ring gear 30 of the planetary gearset 24provides an output to drive the connected turbocharger drive gear 48with increased speed and decreased torque as compared to the speed andtorque of carrier 28.

The turbocharger drive gear 48 drives the idler gear 50 and the meshingcarrier drive gear 54 which in turn drives the shaft 56 and connectedcarrier 58 of the planetary gearset 62. This planetary gearset is alsoconditioned for an overdrive operation since the ring gear 64 is heldfor reaction. Under these conditions the sun gear 66 is driven at aspeed faster than the input provided by carrier 58. The turbine shaft 68with the turbine wheel 70 and impeller 74 connected thereto are drivenas a rotor unit by the sun gear. The air compressor impeller is thusdriven by the engine at increased speed through the gear train asdetermined by the ratios of the two overdrive planetary units to supplysufficient quantities of air to the engine for combustion.

When the engine approaches full load, the exhaust gases acting on theturbine wheel drive the rotor unit faster than the mechanical input.Under these conditions, the direction of torque in the portion of thegear train from the carrier 58 of gear unit 62 to the ring gear 30 ofplanetary gear unit 24 is reversed. The torque on the sun gear 32 is ina forward direction from carrier 28 and in a reverse direction from thering gear 30. The gear ratio of the planetary gearsets are selected sothe torques on the sun gear 32 will be substantially cancelled when theturbine wheel is driving. Thus, the fluid unit 40 operates to divide thedrive train into two separated parts so that the natural frequency ofthe system is not fixed and cannot be excitable by the engine. Thetransmission of engine and output shaft torsionals will be substantiallyreduced as compared to prior systems by increased coupling slip tothereby prevent undue strain on the gear train. Coupling slip alsoprevents an overload on the gear train when the turbine drive suddenlydrops the load on the gear train as when the engine load is dumped.

When the engine is driving the rotor unit for engine starting and lightload operation, the coupling slip absorbs approximately IO percent ofthe torque supplied by the engine to the gear train. This absorption oftorque reduces air flow to the engine under no-load conditions and therewill be less turbine assistance so that the reduction in compressorpower provides for decreased fuel consumption and longer gear trainlife.

The coupling is disposed in a position in the turbocharger assembly foraccessibility for quick inspection and repair if needed. With thissystem the prior one-way clutch has been eliminated although a smallone-way device could be employed between sun gear 32 and spur gear 34 ifdesired or between the turbine 42 and ground to provide for the overrunof the rotor unit. Overrun could also be accomplished by cutting off thesupply of oil to the coupling through passage 43 and replaced by air sothat the oil in the coupling will be evacuated through passage 43. Withthe coupling emptied of drive oil, there would be no drive between thepump and turbine and the pump would be free to spin. Instead ofa fluidcoupling, a hydrodynamic torque converter could readily be used as thefluid unit.

This invention is not limited to the details of the construction shownand described for purposes of illustrating the invention for othermodifications will occur to those skilled in the art.

What is claimed is:

1. In an engine turbocharger drive system, input means, and outputmeans, power transmission means operatively connecting said input andoutput means, said power transmission means comprising a planetary unit,said planetary unit having a first member driven by said input means andhaving a second member drivingly connected to said output means andhaving a third member, a hydrodynamic unit having rotatable pump meansfor circulating fluid therein operatively connected to said thirdmember, said hydrodynamic unit further having turbine means forreceiving fluid exiting from said pump means and for returning fluid tosaid pump means, a stationary member, means operatively connecting saidturbine means to said stationary member so that said third member ofsaid planetary unit connected to said pump means will be limited inspeed and retarted from rotation by the stall torque of saidhydrodynamic unit which increases with increasing rotary speed of saidpump means as said input means drives said first member and said secondmember drives said output means.

2. In a power transmission, transmission input means, transmissionoutput means, a gear train operatively connecting said input and outputmeans, said gear train having a planetary unit, said planetary unithaving a first member driven by said transmission input means and havinga second member drivingly connected to said transmission output meansand having a third member, a hydrodynamic unit having pump meansoperatively connected to said third member and having turbine means, astationary member, means operatively connecting said turbine means tosaid stationary member so that rotation of said third member of saidplanetary unit will be limited by the stall torque of said hydrodynamicunit as said transmission input means drives said first member tocondition said planetary unit for a predetermined speed ratio.

3. In a power transmission, first and second power input means,transmission output means, power transmitting means comprising planetarygearset means operatively connecting said first input means to saidoutput means, said planetary gearset means having input and outputmembers and a reaction member, reaction means operative to retard therotation of said reaction member to condition said planetary gearsetmeans for a predetermined gear ratio for driving said transmissionoutput means in response to the drive of said input member of saidplanetary gearset by said first input means, connector means fordrivingly connecting said second input means to said power transmittingmeans between said planetary gearset means and said output means so thatsaid second input means can drive said output means in the samedirection as said first input means drives said output means and backdrive said output member of said planetary gearset means so that thetorques imposed on said reaction member by said input and output membersare opposite to thereby divide said power transmission into two parts sothat said second input means can drive said output means alone andwithout using power from said first input means.

4. In a power transmission, first and second power input means,transmission output means, power transmission means operativelyconnecting said first input means to said output means, said powertransmission means having first and second operatively connectedplanetary gearsets, each of said gearsets having input and output andreaction members, means drivingly connecting said output of said firstgearset to said input of said second gearset, reaction means operativelyconnected to each of said reaction members for retarding said reactionmembers from rotation to thereby condi tion each said gearset for anoverdrive gear ratio when said first input means drives saidtransmission output means through said power transmission, connectormeans drivingly connected to said power transmission between saidplanetary gearsets and said transmission output means for driving saidoutput and back driving said first planetary gearset means for applyinga torque on said reaction member of said first planetary gearsetopposite to the torque applied thereto by said first input means so thatsaid transmission separates into two systems with said second inputfully driving said output without assistance from said first input.

5. In a power transmission, first and second power input means,transmission output means, power transmission means operativelyconnecting said first input means to said transmission output means,said power transmission means comprising first and second simpleplanetary gearsets, each of said gearsets having an input member and anoutput member and a reaction member, means drivingly connecting saidfirst power input means to said input member of said first planetarygearset, a hydrodynamic unit having first vaned means operativelyconnected to said reaction member of said first gearset and havingsecond vaned means, stationary means operatively connected to saidsecond vaned means to retard said second vaned means from rotation sothat the stall torque of said hydrodynamic unit retards rotation of saidreaction member of said first gearset to condition said first gearsetfor an overdrive gear ratio, means drivingly connecting said outputmember of said first planetary gearset to said input member of saidsecond planetary gearset, means for holding said reaction member of saidsecond gearset from rotation to condition said second gearset for anoverdrive so that said first input can drive said output with a speedincreasing ratio, and means for connecting said second input to saidpower transmission means between said second gearset and said outputmeans so that said second power input means can drive said transmissionoutput means and back drive the output member of said first planetarygearset.

6. In a power transmission, first and second power input means,transmission output means, power transmission means operativelyconnecting said first input means to said transmission output means,said power transmission means comprising first and second planetarygearsets, each of said gearsets having an input member and an outputmember and a reaction member, means drivingly connecting said firstinput means to said input member of said first planetary gearset, ahydrodynamic fluid coupling unit having vaned pump means operativelyconnected to said reaction member of said first gearset and having vanedturbine means forming a torus in which transmission fluid is circulated,stationary means operatively connected to said turbine means to preventsaid turbine means from rotation so that the stall torque of said fluidcoupling retards rotation of said reaction member of said first gearsetto condltion said first gearset for an overdrive gear ratio, meansdrivingly connecting said output member of said first planetary gearsetto said input member of said second planetary gearset, means for-

1. In an engine turbocharger drive system, input means, and outputmeans, power transmission means operatively connecting said input andoutput means, said power transmission means comprising a planetary unit,said planetary unit having a first member driven by said input means andHaving a second member drivingly connected to said output means andhaving a third member, a hydrodynamic unit having rotatable pump meansfor circulating fluid therein operatively connected to said thirdmember, said hydrodynamic unit further having turbine means forreceiving fluid exiting from said pump means and for returning fluid tosaid pump means, a stationary member, means operatively connecting saidturbine means to said stationary member so that said third member ofsaid planetary unit connected to said pump means will be limited inspeed and retarted from rotation by the stall torque of saidhydrodynamic unit which increases with increasing rotary speed of saidpump means as said input means drives said first member and said secondmember drives said output means.
 2. In a power transmission,transmission input means, transmission output means, a gear trainoperatively connecting said input and output means, said gear trainhaving a planetary unit, said planetary unit having a first memberdriven by said transmission input means and having a second memberdrivingly connected to said transmission output means and having a thirdmember, a hydrodynamic unit having pump means operatively connected tosaid third member and having turbine means, a stationary member, meansoperatively connecting said turbine means to said stationary member sothat rotation of said third member of said planetary unit will belimited by the stall torque of said hydrodynamic unit as saidtransmission input means drives said first member to condition saidplanetary unit for a predetermined speed ratio.
 3. In a powertransmission, first and second power input means, transmission outputmeans, power transmitting means comprising planetary gearset meansoperatively connecting said first input means to said output means, saidplanetary gearset means having input and output members and a reactionmember, reaction means operative to retard the rotation of said reactionmember to condition said planetary gearset means for a predeterminedgear ratio for driving said transmission output means in response to thedrive of said input member of said planetary gearset by said first inputmeans, connector means for drivingly connecting said second input meansto said power transmitting means between said planetary gearset meansand said output means so that said second input means can drive saidoutput means in the same direction as said first input means drives saidoutput means and back drive said output member of said planetary gearsetmeans so that the torques imposed on said reaction member by said inputand output members are opposite to thereby divide said powertransmission into two parts so that said second input means can drivesaid output means alone and without using power from said first inputmeans.
 4. In a power transmission, first and second power input means,transmission output means, power transmission means operativelyconnecting said first input means to said output means, said powertransmission means having first and second operatively connectedplanetary gearsets, each of said gearsets having input and output andreaction members, means drivingly connecting said output of said firstgearset to said input of said second gearset, reaction means operativelyconnected to each of said reaction members for retarding said reactionmembers from rotation to thereby condition each said gearset for anoverdrive gear ratio when said first input means drives saidtransmission output means through said power transmission, connectormeans drivingly connected to said power transmission between saidplanetary gearsets and said transmission output means for driving saidoutput and back driving said first planetary gearset means for applyinga torque on said reaction member of said first planetary gearsetopposite to the torque applied thereto by said first input means so thatsaid transmission separates into two systems with said second inputfully driving said output without assistance from said first input. 5.In a power transmission, first and second power input means,transmission output means, power transmission means operativelyconnecting said first input means to said transmission output means,said power transmission means comprising first and second simpleplanetary gearsets, each of said gearsets having an input member and anoutput member and a reaction member, means drivingly connecting saidfirst power input means to said input member of said first planetarygearset, a hydrodynamic unit having first vaned means operativelyconnected to said reaction member of said first gearset and havingsecond vaned means, stationary means operatively connected to saidsecond vaned means to retard said second vaned means from rotation sothat the stall torque of said hydrodynamic unit retards rotation of saidreaction member of said first gearset to condition said first gearsetfor an overdrive gear ratio, means drivingly connecting said outputmember of said first planetary gearset to said input member of saidsecond planetary gearset, means for holding said reaction member of saidsecond gearset from rotation to condition said second gearset for anoverdrive so that said first input can drive said output with a speedincreasing ratio, and means for connecting said second input to saidpower transmission means between said second gearset and said outputmeans so that said second power input means can drive said transmissionoutput means and back drive the output member of said first planetarygearset.
 6. In a power transmission, first and second power input means,transmission output means, power transmission means operativelyconnecting said first input means to said transmission output means,said power transmission means comprising first and second planetarygearsets, each of said gearsets having an input member and an outputmember and a reaction member, means drivingly connecting said firstinput means to said input member of said first planetary gearset, ahydrodynamic fluid coupling unit having vaned pump means operativelyconnected to said reaction member of said first gearset and having vanedturbine means forming a torus in which transmission fluid is circulated,stationary means operatively connected to said turbine means to preventsaid turbine means from rotation so that the stall torque of said fluidcoupling retards rotation of said reaction member of said first gearsetto condition said first gearset for an overdrive gear ratio, meansdrivingly connecting said output member of said first planetary gearsetto said input member of said second planetary gearset, means for holdingsaid reaction member of said second gearset from rotation to conditionsaid second gearset for an overdrive gear ratio so that said first inputcan drive said output with a speed increasing ratio, and means forconnecting said second input to said power transmission means betweensaid second gearset and said transmission output means so that saidsecond power input means can drive said transmission output meanswithout assistance from said first input means while back driving saidsecond planetary gearset and the output member of said first planetarygearset.